Generally, various safety devices for protecting a driver and a passenger against unexpected situations which may occur at some time are provided in an automobile, and representatively, an airbag device for directly protecting the driver and the passenger seated in a front seat of the automobile is included.
When an impact to the automobile occurs, compression gas is momentarily injected into the airbag by impact force and thus, the air bag device covers front sides of the driver and the passenger in the front seats while the airbag is expanded at a rapid speed to protect the driver and the passenger from windshield glass of the automobile or a front object.
Generally, a representative type of front impact includes 100% front, offset, oblique, or pole impacts. In the case where a passenger restriction device is controlled by using a deceleration measured by an air-bag control unit (ACU) mounted in a passenger boarding chamber, performance of the 100% front and pole impacts may be secured, but performance of the offset and oblique impacts is hardly secured. In the case of the offset and oblique impacts, even though an impact degree is severe, a magnitude of the deceleration in the ACU which occurs at an early stage of the impact is not large, and as a result, it is difficult to control the passenger restriction device.
In order to solve the problem, a front impact sensor (FIS) is mounted on the front of the automobile. The FIS is used to sense the deformation of the front of the automobile at the early stage while mounted at the front of the automobile. The passenger restriction device is controlled by using the deceleration obtained therefrom together. Further, in order to prevent a malfunction of the passenger restriction device due to a malfunction of the sensor, a separate shaping sensor is mounted to operate the passenger restriction device only when the shaping sensor determines the impact.
In the case of using the FIS, the performance of the offset and oblique impact may be secured, but there is a problem as follows. Since the sensor is mounted at the front of the automobile, the sensor during the impact is broken or a wire harness connecting the sensor and the ACU may be cut. Further, there is a problem in that cost is increased due to the addition of two left and right FISs and the wire harness.